1. Field of the Invention
The present invention relates to a capacitor-based reserve d.c. power device that can be used to mask short-lived power cuts in a d.c. power supply network for electronic modules.
2. Description of the Prior Art
One of the possible applications of a reserve d.c. power device is the supply of direct current to items of equipment on board an aircraft. Direct current power supply systems on board aircraft undergo cutoffs lasting some microseconds to some tens of milliseconds. These power cutoffs are caused by the starting up of devices that are heavy consumers of power, for example electrical motors or by a transfer from one power source to another by means of electromechanical switching devices. These power cutoffs can be detrimental to the efficient working of electronic equipment, should they reach this equipment. To avert this possibility, it is common practice to use power reserve devices based on electrolytic capacitors. These power reserve devices are positioned immediately upline from the electronic devices. They take over the role of the power supply system during the micro-cutoffs.
These power reserve devices raise problems of dependability owing to the possible breakdown of their capacitors, which may get short-circuited or pass into an state of open circuit. Malfunctioning through the short-circuiting of an electrolytic capacitor of a power reserve device is easy to detect because it causes the electronic equipment that is being powered to become unavailable. The probability of this malfunction is about 0.5 10.sup.31 6 per capacitor. The malfunctioning that occurs when the electrolytic capacitor of a power reserve device goes into a state of open circuit is more subtle for it is apparent only in a deterioration of the time during which the cutoffs are masked. Its probability too is in the range of 0.5 10.sup.31 6 per capacitor.